Help, I have no friends! Advice?

I'm a 23 year old first time mum to a 4 month old baby. Ever since leaving school when you all go your separate ways I haven't really had any friends. There is 1 girl who I keep in touch with and see every few months but she is always too busy to meet up more often.
It's starting to depress me a bit that I haven't really got any friends to turn to or even just chat with and go on days out with whilst me partner is at work. Some days the only person I speak/ see is my partner.
Have any of you got no friends and are ok with it?
 Or does anyone have any tips on how would be best to make some new friends. I'm very wary about imposing on other peoples friendships and get a bit anxious about trying to make new friends 😕 I feel like it's a no win situation sometimes. 
Thanks in advance.